but the point is you could disconnect the hdd
and the PSU wouldnt draw that much more power
p.s. this is totally useless and i am going to stop posting about this but overall ADG is wrong
No, he isn't. the Hard Drive motors are (some) of the more power-drawing components of a PC, and they do NOT need to be running all the time. The "wear" I describe above it negligible(if they even exist at all, It's pure conjecture, really; it seems logical, to assume that there is some amount of wear on the drive, however it is probably not even worth mention at all, heck if we wanted our drives to last forever we'd never turn them on anyway!. Their power draw DOES influence what the PSU draws from the wall, (depending on the PSU itself, as well). this is what the "switching" and load compensation in a PSU is for- when a component stops drawing power from a rail, say, a floppy stops spinning, or, in this case, a HD motor spins down- with it's 12v rail now missing load, the PSU might still try to "push" through the same amount of current as it was when it was required. However, the "load-balancing" common in most Power supplies stops this, detects the lighter load and the PSU sends only what current is needed.
in general the DC output current is proportional to the AC current draw, which directly affects, in some way, the electric bill, and of course the other concerns mentioned.